Reducing formaldehyde emissions in formal-containing compositions

ABSTRACT

Method for reducing the formaldehyde emission of a composition containing a formal by adding urea, urea derivatives, amino acids, guanidine or guanidine derivatives.

The present invention relates to a preservative with reducedformaldehyde emission, and to the preparation and use thereof.

Formaldehyde donor compounds, for example O-formals and N-formals, areused as biocides in a series of products and preparations for reducingmicrobial growth. A series of documents is known which describe the useof O-formals and N-formals.

DE-42 42 082 A1 discloses hydrolyzable polymeric resins and binders forantifouling paints. As well as hydrolyzable polymeric resin, the bindersystem can also comprise cobiocides, such as dichlorophenyl-dimethylureaor 2-methylthio-4-tert-butylamino-6-cyclo-propylamino-s-triazine.

U.S. Pat. No. 4,655,815 discloses a synergistic antimicrobial mixture of2-bromo-2-bromomethylglutaronitrile and formaldehyde donor. Examples offormaldehyde donors are 2-[(hydroxymethyl)amino]-2-methylpropanol,2-hydroxy-ethyl-2-nitro-1,3-propanediol, mixtures of5-hydroxy-methyl-1-aza-3,7-dioxabicyclo-(3.3.0)octane,2-[(hydroxymethyl)amino]ethanol,1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride,N-(3-chloroallyl)heximinium chloride, hexamethylenetetramine(hexamine)halohydrocarbon quats and dimethyloldimethylhydantoin.

GB-2 274 779 A discloses a microbicidal formulation which consists of amixture of a sulphur-containing aromatic compound and a triazinecompound, dissolved in a solvent. The sulphur-containing aromaticcompound can, for example, be an isothiazolone derivative, the thiazinecompound may be 2,2′,2″-(hexahydro-1,3,5-triazine-1,3,5-triyl)triethanol(triazinetriethanol, Grotan BK).

EP-0 327 220 B1 describes a synergistic combination of selectedformaldehyde donor with iodopropargyl compound. The disclosedcompositions comprise, as preferred iodopropargyl compound, iodopropynylbutyl-carbamate (IPBC) and, as formaldehyde donors, nontoxic andodour-free compounds which are suitable for use in bodycarecompositions. Examples of formaldehyde donors are imidazolidinylurea(=Germall115=N,N″-methylene-bis(N′-(3-hydroxymethyl)-2,5-dioxoimidazolidin-4-yl)urea),diazolidinylurea (=imidazolidinylurea II=GermallII=1-(1,3-bis(hydroxymethyl)-2,5-dioxoimidazolidin-4-yl)-1,3-bis(hydroxymethyl)urea),cis-isomer of 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride(=Dowicil 200), 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantanechloride (=quaternium 15=Dowicil 100), DMDMH(=1,3-dimethylol-5,5-dimethylhydantoin). However, said formaldehydedonors are relatively expensive substances, the use of which forpreserving technical mass-produced products is prohibited for reasons ofcost alone.

DE-41 41 953 discloses microbicidal compositions which comprise, asactive ingredients, a combination of at least one iodopropargylderivative and benzyl alcohol mono(poly)hemiformal. Moreover, furthercompounds, e.g. formaldehyde or its donor substances or guanidinederivatives, can be added to the active ingredient combination.

U.S. Pat. No. 5,428,050 and U.S. Pat. No. 5,496,842 disclose awater-soluble preservative mixture which comprises powders of (a) one ormore methylol compounds or equivalents thereof, and (b) iodopropynylalcohol, its ester, carbamate or ether derivative, in a weight ratio of(a):(b) of from 100 to 2000:1. The patent specifications disclose thesynergistic combination of (a) and (b). However, undesired formaldehydeemissions are not discussed.

DE-197 22 858 A1 relates to compositions based on iodopropynyl andformaldehyde donor compounds and use thereof as preservatives. Examplesof formaldehyde donor compounds areN,N′-methylenebis(5-methyl-oxazolidine),3,3′-methylenebis(tetrahydro-2H-1,3-oxazine) and1-aza-5-ethyl-3,7-dioxabicyclo[3.3.0]-octane. The compositions of DE-19722 858 A1 comprise iodopropynyl butylcarbamate as preferred iodopropynylcompound. As the IPBC content increases, the formaldehyde emissionsincrease, thus the biocidal effectiveness of the compositions in the gasphase also increases with increasing IPBC content. In the compositions,an addition of certain glycols has a positive influence on the odour ofthe compositions and reduces the emission of relatively volatilesubstances such as, for example, formaldehyde.

The use of compositions which comprise iodopropynyl compounds is thusprecluded if particularly low formaldehyde emissions are desired, or inthe case of use in environments which are incompatible with iodopropynylcompounds. Moreover, compositions which comprise iodopropynyl compoundshave a tendency toward undesired discolorations.

The preservative of DE-40 26 756 A1 comprises a mixture of (a) anorganic acid, (b) a monophenyl glycol ether and (c) a guanidinederivative. Further optional biocides mentioned are imidazolidineureaand/or hydantoin derivatives.

DE-199 61 621 A1 relates to compositions which comprise at least onebactericidal N-formal, at least one fungicide and at least onestabilizer. Particularly preferred formals are triazinetriethanol andN,N′-methylenebis(5-methyloxazolidine).

198 42 116 A1 discloses stable microbicidal compositions which comprisederivatives of methylene-bisoxazolidine and 1H-benzimidazol-2-ylcarbamicacid. Moreover, further active ingredients may be present, for exampledimethylolurea, bis(hydroxymethyl)-5,5-dimethylhydantoin,diazolidinylurea, sodium hydroxyl-methylglycinate or diuron(1,1-dimethyl-3-(3,4-dichlorophenyl)urea. However, these substances arerelatively expensive and/or toxic. Carbendazime(methyl1H-benzimidazol-2-ylcarbamate) is regarded as undesired due to its toxicproperties (cancerogenic, mutagenic, reproduction-toxic) and itsclassification as a toxic substance (from 0.1% use concentration),although it is difficult to replace due to its good microbicidal effect.

In addition, various technical products based on N/O-formal are known.Thus, for example, the reaction product of formaldehyde orparaformaldehyde and ethanolamine (GrotanBK=N,N′,N″-tris(hydroxy-ethyl)hexahydrotriazine) has been usedsuccessfully as a preservative in the cutting fluid sector. Grotan BK isa colourless to slightly yellowish liquid with a characteristic odour.On the basis of legal provisions, it has become a requirement to label apreparation containing greater than or equal to 0.1% ofhexahydro-triazine (labelling requirement from 0.1% of hexahydrotriazineas R 43). In practice, a labelling of such substances or preparations(e.g. cutting fluid emulsions) cannot be carried out. As alternatives,therefore, biocides are sought which do not lead to a correspondinglabelling, but on the other hand are comparatively effective,cost-effective and are acceptable from organoleptic considerations.These biocides should not necessarily comprise a large amount ofhexahydrotriazine, but at the same time can release a large amount offormaldehyde, based on the weight.

An alternative to Grotan BK which is used is, inter alia, the 1:1condensation product of paraformaldehyde and isopropanolamine(N,N,N″-tris(β-hydroxypropyl)hexahydrotriazine, Grotan WS). Grotan WSis, due to the lower content of formaldehyde, somewhat less effectivethan Grotan BK, and is also more odour-intensive and significantly moreexpensive than Grotan BK.

For many years, a condensation product of paraformaldehyde andisopropanolamine (weight ratio 3:2, Mar 71 or Grotan OX or GrotaMar 71,N,N′-methylenebis(5-methyloxazolidine) has also been used. Thecommercial products are anhydrous or low-water, colourless to slightlyyellowish liquids with a characteristic pungent odour reminiscent ofamine and formaldehyde. The biocidal effectiveness is very good due tothe comparatively high formaldehyde content. However, the odour isperceived as a disadvantage during use. In particular, the pungent odourreminiscent of formaldehyde and the formaldehyde emission have beencriticized.

Although, as has been mentioned, it is known from DE 197 22 858 A1 thatcertain glycols have a positive influence on the odour of compositionswhich comprise formaldehyde donor compounds and can reduce the emissionof relatively volatile substances such as formaldehyde, the addition ofrelatively large amounts of odour-modifying additive, however, reduces,in an undesired way, the active ingredient content, based on the totalweight. At the same time, emissions of odour-modifying additive(solvent) automatically arise, these emissions are in turn undesired.

Preparations based on dimethyloldimethylhydantoin (DMDMH) ortetramethylolglycoluril are also known. Apart from the fact that DMDMHand tetramethylolglycoluril are relatively expensive, they are solids oraqueous preparations which are unsuitable for certain fields ofapplication. For example, it is impractical if, in the preparation of adilute cutting fluid, a solid additive has firstly to be dissolved. Inaddition, a water fraction often has an unfavourable effect on the(storage) stability of certain active ingredients. Aqueous preparationsalso often have inadequate low-temperature stability. Waterautomatically reduces a high formaldehyde content and has anunfavourable effect on the emission of volatile constituents.

An object of the present invention was consequently to provide aformaldehyde donor preparation as preservative for cutting fluidconcentrates and cutting fluid emulsions, technical emulsions or asbiocidal additive for products (e.g. diesel fuel) or in processes (e.g.in the offshore sector, boring fluids). This preparation should

-   1. be able to be formulated in a cost-effective manner,-   2. release comparatively small amounts of formaldehyde into the gas    phase,-   3. be acceptable in terms of odour,-   4. have a high content of formaldehyde which can be cleaved off,    i.e. the preparation should not automatically have a high solvent    content,-   5. be storage-stable, even over a prolonged period,-   6. be miscible with further known biocidal, anti-microbial active    ingredients and functional additives or auxiliaries without    incompatibilities arising,-   7. be able to be formulated in various forms, i.e. as a solid,    semisolid, pasty or liquid preparation, and-   8. be able to be formulated on the basis of formaldehyde donor    compounds on the market, so that no new approval proceedings are    necessary.

According to the invention, it has now been found that this object isachieved by a preservative according to claim 1, which comprises a) atleast one formal and b) at least one emission-reducing additive which ischosen from urea, urea derivatives, amino acids, guanidine and guanidinederivatives, where the preservative (i) comprises no iodopropynylcompound and (ii) no derivative of 1H-benzimidazol-2-ylcarbamic acid.

Preferred embodiments are the subject-matter of the dependent claims.

The formal used according to the invention is preferably a N- and/orO-formal. Examples of such formaldehyde donor compounds are N-formalswhich are a reaction product or condensation product of a mono- orpolyhydric, amino-substituted C₁- to C₁₀-alkyl-, -aryl-, -aralkylalcoholand a formaldehyde-supplying compound, and/or O-formals which arereaction products of a mono- or polyhydric C₁- to C₁₀-alkyl-, -aryl-,-aralkylalcohol or a glycol or glycol ether and a formaldehyde-supplyingcompound.

Examples of O-formals are (ethylenedioxy)dimethanol, benzyl alcoholhemiformal, propylene glycol hemiformal and butyl diglycol hemiformal.Examples of N-formals are N,N′,N″-tris(hydroxyethyl)hexahydrotriazine,N,N′,N″-tris(β-hydroxypropyl)hexahydrotriazine,N-methylolchloroacetamide, cis-isomer of1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride,1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride,5-(polyoxymethylene)-1-aza-3,7-dioxabicyclo[3.3.0]-octane,({[1-methyl-2-(5-methyloxazolidin-3-yl)ethoxy]-methoxy}methoxy)methanol,4,4-dimethyloxazolidine, 7a-ethyldihydro-1H,3H,5H-oxazolo[3,4-c]oxazole,2-(hydroxymethylamino)ethanol, 1-(hydroxymethylamino)propan-2-ol andN,N′-methylenebis(5-methyloxazolidine). According to the invention,particular preference is given toN,N′-methylenebis(5-methyl-oxazolidine).

Examples of emission-reducing additives are chosen from glycoluril,tetramethylolglycoluril, dimethylhydantoin, dimethyloldimethylhydantoin,dimethylolurea, tetramethylolurea, imidazolidinylurea anddiazolidinylurea. A particularly preferred emission-reducing additive isurea.

A compound which is covered by the definition of an emission-reducingadditive is per definitionem no formal (a) for the purposes of thedescription of the present invention. The emission-reducing additive canthus itself be a formal (a formaldehyde donor compound) (such astetramethylolurea) and thus reduce the necessary amount of formal (a),which is advantageous if the formal (a) is a hexahydrotriazine.

The preservative according to the invention can also comprise one ormore odour-modifying additives, such as alcohols, glycols and glycolethers, where phenoxy-ethanol, phenoxypropanols, benzyl alcohol,phenethyl alcohol, phenylpropanols, phenylbutanols and phenyl-pentanolsare particularly suitable, particular preference being given tophenoxyethanol. A further preferred odour-modifying additive is majantol(phenylpentanol).

Moreover, the preservative can comprise one or more biocides, forexample boric esters, boric acid salts, lactic acid derivatives,isothiazolones, pyridine derivatives, phenols and parabens.

Examples of further biocides which can be used according to theinvention can also be found in the BPD (Biocidal Product Directive) listof active ingredients. The combination with these known biocides servesto extend the spectrum of activity and/or to achieve synergisticincreases in activity. Particular preference is given to combinationswith thiabendazol, 2-mercaptopyridine N-oxide derivatives, such aspyrion-Na, zinc pyrithione, isothiazolones, such asN-octylisothiazolone, 4,5-dichloro-N-octylisothiazolone,N-methylisothiazolone, kathon 886, benzisothiazolone,n-butylbenzisothiazolone, phenols, such as o-phenylphenol, parabens,thiophene compounds, such as N-cyclohexylbenzothiophene-2-carboxamideS,S-dioxide, amines, such as 2-amino-2-methylpropanol, quaternaryammonium salts such as benzalkonium chloride, didecyldimethylammoniumchloride, Vantocil IB, aldehydes, such as glutardialdehyde ando-phthaldialdehyde, and also active oxygen compounds, such as tert-butylhydroperoxide.

The preservative according to the invention can also comprise (e) one ormore additives, for example solvents, solubility promoters, corrosioninhibitors, alkalinizing agents, dyes, perfume, viscosity-modifyingagents, foam inhibitors, emulsifiers, and antioxidants, dispersants,complexing agents, wetting agents, cleaning components, surfactants,pigments, ethereal oils, lubricant additives, care additives, fillersand polymers. Preferably, the preservative according to the invention,however, comprises no hydrolyzable, polymeric resin.

A preferred embodiment of the invention relates to a preservative inwhich the weight ratio (a):(b) is in the range from 500:1 to 1:1,preferably 200:1 to 5:1, more preferably 100:1 to 10:1 and in particular50:1 to 20:1. Odour-modifying additives may be present in amounts offrom 0 to 20% by weight, preferably 1 to 10% by weight, particularlypreferably 4 to 8% by weight, based on the total weight of thepreservative. In a further embodiment, the odour-modifying additive canbe present in an amount of 90% by weight or less, preferably 40% byweight or less and particularly preferably 20% by weight or less, basedon the total weight of the preservative.

In a preferred embodiment, the preservative according to the inventionconsists of a) formal, b) emission-reducing additive and optionally c)odour-reducing additive and possibly a small amount of water (up to 10%by weight of water, preferably up to 5% by weight).

A further preferred embodiment relates to a preservative which comprises

-   a) 90 to 99% by weight, preferably 92 to 98% by weight, more    preferably 93 to 97% by weight, in particular about 95% by weight,    of N,N′-methylenebis(5-methyloxazolidine) and-   b) 1 to 10% by weight, preferably 2 to 8% by weight, more preferably    3 to 7% by weight, in particular about 5% by weight, of urea,    for example a preservative which consists of these two components in    said amounts.

A further preferred embodiment relates to a preservative which comprises

-   a) 80 to 98% by weight, preferably 84 to 96% by weight, more    preferably 86 to 94% by weight, in particular about 90% by weight,    of N,N′-methylenebis(5-methyloxazolidine),-   b) 1 to 10% by weight, preferably 2 to 8% by weight, more preferably    2 to 7% by weight, in particular about 5% by weight, of urea and-   c) 1 to 10% by weight, preferably 2 to 8% by weight, more preferably    3 to 7% by weight, in particular about 5% by weight, of    phenoxyethanol,    for example preference is given to a preservative which consists of    these three components in said amounts.

It is possible to formulate the preservative according to the inventionby simply mixing component a) with component b) and optionally furtherconstituents. However, a preferred preparation variant relates to aprocess in which

-   a) at least one amine and/or alcohol is initially introduced,-   b) formaldehyde is added,-   c) the mixture is optionally heated to a temperature in the range    from 50° C. to 100° C.,-   d) at least one emission-reducing additive is added which is chosen    from urea, urea derivatives, amino acids, guanidine and guanidine    derivatives,-   e) the mixture is optionally heated to a temperature in the range    from 50° C. to 100° C. and-   f) optionally odour-modifying additive is added which is chosen from    alcohols, glycols and glycol ethers.

Preferably, odour-reducing additive is only added shortly prior to thepreservative being used.

In a preferred embodiment of the process according to the invention

-   -   the temperature of step c) is in the range from 60° C. to 80°        C., in particular about 70° C., and    -   the temperature of step e) is in the range from 60° C. to 80°        C., in particular about 70° C., and additionally in step e)        water is distilled off under reduced pressure.

In this preferred embodiment, particularly low formaldehyde emissionsare observed for the preservative thus prepared.

In addition, the invention relates to the use of a preservativeaccording to the invention for preserving a technical product, such as acutting fluid, propellant, surface coating, a dispersion or awater-based paint.

Moreover, the invention relates to the use of urea, urea derivatives,amino acids, guanidine or guanidine derivatives for reducing theformaldehyde emission of a composition which comprises a formal.

The preservatives according to the invention may be solid, semisolid,pasty or liquid, they are preferably liquid. In a further preferredembodiment, the preservatives have a low content of water, for examplethey comprise 10% by weight of water or less, preferably 5% by weight orless, in particular 1% by weight or less of water, particular preferencebeing given to anhydrous preservatives.

The preservative according to the invention offers, inter alia, thefollowing advantages:

-   -   it can be formulated in a cost-effective manner from standard        commercial components,    -   it has a high formaldehyde content, but at the same time greatly        reduces formaldehyde emissions (gas phase),    -   it can be formulated in diverse forms, for example in a mixture        with further biocides,    -   it has good storage stability, the slight clouding or        precipitates sometimes observed with pure liquid formals such as        Grotan OX do not arise in the case of the preservative according        to the invention,    -   through the addition of the emission-reducing additive it is        possible to reduce the nonvolatile and volatile nitrosamines        which form in small amounts in certain applications (e.g. as        preservatives in cutting fluid emulsions),    -   upon storage in plastic containers, no neck-in effect arises,        resulting in a cost saving (the plastic containers can be reused        more often).

Formals are used to prevent microbial deposits on filters and in tankplants as fuel additive, also in modern speciality fuels which representan emulsion of diesel fuel in water. An addition of urea to formal (suchas N,N′-methylenebis(5-methyloxazolidine)) does not only reduce theemission of formaldehyde or formaldehyde donor compounds, but alsobrings about a reduction in the NO emission upon combustion of thepropellant equipped with the preservative according to the invention.

These and further advantages are also evident from the examples below.

EXAMPLES

Grotan OX is N,N′-methylenebis(5-methyloxazolidine). Protectol 140 istetramethylolacetylenediurea.

1. Method of Determining Formaldehyde in the Gas Phase

-   -   The determination of the formaldehyde content in the gas phase        above various preservatives was carried out using Dräger tubes        0.2/a (No. 6733081) in accordance with the instructions for use        from Dräger-Sicherheitstechnik GmbH (8^(th) Edition, May 1999).        For this purpose, about 100 g of the sample to be investigated        were introduced into a 250 ml wide-necked beaker with a screw        lid and left to stand, in the closed state, for at least three        hours at room temperature. The measurement was read off after        two strokes on the scale 0.5 to 5 ppm, n=10. The measurements        were carried out under comparable external conditions. Although        the measurement results do not indicate an absolutely exact        value in ppm of formaldehyde, the method is highly suitable for        differentiating the formaldehyde emissions of different samples.

2. Method of Determining Formaldehyde in the Liquid Phase

-   -   Basis: The formaldehyde to be determined is expelled from the        matrix using steam distillation (steam distillation apparatus        according to Antona). The steam/formaldehyde mixture is passed        over a distillation bridge and condenses on a high-efficiency        condenser. The condensate is collected in a measuring flask. One        aliquot fraction of this water/formaldehyde mixture is reacted.        The formaldehyde condenses with 2,4-pentanedione in the presence        of ammonium salts to give 3,5-diacetyl-1,4-dihydrolutidine. The        resulting 3,5-diacetyl-1,4-dihydrolutidine is bright yellow in        colour. Following an upstream steam distillation, apart from        acetaldehyde in excess, no undesired substance is known.    -   Formaldehyde reagent: 75.0 g of ammonium acetate p.a. 1.5 ml of        glacial acetic acid p.a. 1.0 ml of acetylacetone        (2,4-pentanedione) for spectroscopy=>made up with demineralized        water (demin. water) to 500 ml (volumetric flask)    -   Procedure: The size of the initial weight is governed by the        formaldehyde content to be expected in the sample. Subsequent        steam distillation is carried out to a value of 100 ml (or 250        ml). The formaldehyde content in the distillate should be 0.10        mg/l to 0.2 mg/l, so that 5-20 ml of the distillate can be        reacted. In the case of water-soluble samples with a higher        formaldehyde content (no direct distillation possible), a        corresponding initial weight is weighed into a 100 ml volumetric        flask and made up with demin. water. 5 to 10 ml of this solution        are used for the reaction. In the case of water-insoluble        samples, the initial weight is rinsed over with demin. water        into the Antona charge, or it is weighed directly into the        charge.    -   The sample to be distilled is treated with 10 ml of 20% strength        sulphuric acid (depending on the objective, a neutral or        alkaline distillation is also possible). To check the        quantitative distillation, after the intended volume has been        distilled off, additionally about 1 ml of distillate can be        tested with 1 ml of formaldehyde reagent in the beaker with        warming with regard to a formaldehyde reaction.    -   2 to 20 ml of the distillate (100 ml or 250 ml) are placed in a        25 ml volumetric flask and treated with 5 ml of formaldehyde        reagent and made up to 25 ml with demin. water. The flask is        placed into a waterbath at 40° C. for 30 mins. After cooling to        room temperature, the absorbance of the solution is measured in        1 cm glass cells in a UV photometer at 412 nm against a blank        (blank: 5 ml of formaldehyde reagent are made up to 25 ml with        demin. water and also heated at 40° C. for 30 minutes).    -   Evaluation: The formaldehyde samples are evaluated against a        formaldehyde calibration curve on the UV photometer.    -   Calibration curve: The calibration curve is constructed by        appropriate initial weighing and dilution of the 37%        formaldehyde solution, steam distillation not being required.        The solutions for the calibration curve are added to 25 ml        volumetric flasks, treated with 5 ml of formaldehyde reagent and        made up with demin. water. The flasks are placed into a        waterbath at 40° C. for 30 minutes and, after cooling to room        temperature, measured against a blank at 412 nm.

3. Method of Preparing Preservatives According to the Invention

Method A

-   -   The preservative was formulated by simple mixing of formal with        emission-reducing additive. The mixture was stirred until a        clear solution was formed. If necessary, the solution was        filtered. The odour of the preservative is significantly        improved compared to Grotan OX, in particular the pungent        formaldehyde odour is greatly reduced, the odour impression        corresponds more closely to that of isopropanolamine.

Method B

-   -   Corresponds to method A, except that the mixing is carried out        with heating.

Method C

-   -   901.3 g (12 mol) of 2-hydroxypropylamine were initially        introduced and 592.0 g (12 mol) of paraformaldehyde (91.3%        strength) were introduced with stirring such that 70° C. was not        exceeded. When the addition was complete, the mixture was        further stirred for 2 hours at 70° C. 46.5 g of urea were then        added and water (in total 365 g) was distilled off under reduced        pressure at 70° C. The mixture was filtered in order to produce        a colourless liquid. The efflux time of a preservative prepared        in this way from a DIN beaker 4 mm is 140 seconds at 20° C.        (compared with Grotan OX 22 seconds). The efflux time from the        DIN beaker 6 mm is 13 seconds at 20° C. (Grotan OX 6 seconds).        The pH, as a 1% strength solution in demineralized water, is        10.5, the formaldehyde content is 45.3% by weight, the        isopropanolamine content is 76.3% and the water content is 0.3%        by weight. The formaldehyde content in the gas phase is less        than 0.5 ppm (Grotan OX 3 to 5 ppm).

4. Determination of the Formaldehyde Emissions of Preservatives

-   -   In the gas phase of preservatives formulated as described, using        the method described under 1., the following formaldehyde        concentrations were measured in the gas phase (Table 1):

Preparation HCHO content process in the gas % by (stirring phase No.Constituent wt. conditions) Blank 1 month 1 Grotan OX 100 — 3-5 3 2Grotan OX 50 A >>5 >>5 Protectol 140 50 3 Groton OX 90 A >>5 >>5demineralized water 10 4 Grotan OX 95 B 1-2 1-2 urea 5 5 Grotan OX 90 A3-5 3-5 urea 5 water 5 6 Grotan OX 90 B 1-2 1-2 urea 5 phenoxyethanol 57 Grotan OX 98 A (1 day) 2-3 3 urea 2 8 Grotan OX 96 A (3 days) 0.5-1  1-2 urea 4 9 Grotan OX 96 B (70° C., 2 h) 0.5-1   1 urea 4 10 Grotan OX96 C 0 0 urea 4 11 Grotan OX 96 A 0.5 5,5-dimethylhydantoin 4

Table 1 shows that the formaldehyde content in the gas phase of awater-containing preservative (No. 3) is significantly increasedcompared to Grotan OX (No. 1), this increase can be compensated byadding urea (No. 5). In anhydrous formulations, the formaldehyde contentin the gas phase is significantly and permanently reduced from a ureacontent of about 2% by weight. However, since in the case of a contentof 4% by weight of urea or more, it is necessary to stir either for 3days at room temperature or for 2 hours at 70° C. in order to obtain acompletely homogeneous mixture, it is advantageous to add the ureaduring the preparation of Grotan OX, specifically after the reactionbetween alkanolamine (2-hydroxypropylamine) with formaldehyde iscomplete, and before the water is distilled off (process C).

The invention claimed is:
 1. A method of reducing the formaldehydeemissions of a composition comprising a formal, comprising: adding atleast one component to a composition comprising at least one formal,wherein the at least one component is selected from the group consistingof: urea, urea derivatives, amino acids, guanidine and guanidinederivatives and wherein the at least one formal is selected from thegroup consisting of an N-formal, an O-formal and a combination thereof.2. The method according to claim 1, wherein the at least one componentis a urea derivative and the urea derivative is selected from the groupconsisting of: glycoluril, tetramethylolglycoluril, dimethylhydantoin,dimethyloldimethylhydantoin, dimethylolurea, tetramethanolurea,imidazolidinylurea, and diazolidinylurea.
 3. The method according toclaim 1, wherein the at least one formal is an O-formal selected fromthe group consisting of dimethanol, benzyl alcohol hemiformal, propyleneglycol hemiformal, and butyl diglycol hemiformal.
 4. The methodaccording to claim 1, wherein the at least one formal is an N-formalselected from the group consisting of:N,N′,N″-tris(hydroxyethyl)hexahydrotriazine,N,N′,N″-trisβ-hydroxypropyl)hexahydrotriazine, andN,N′-methylenebis(5-methyloxazolidine).
 5. The method according to claim1, wherein the at least one component is added to the composition in anamount so that the weight ratio of said at least one formal to said atleast one component is 500:1 to 1:1.
 6. The method according to claim 4,wherein the weight ratio of said at least one formal to said at leastone component is 200:1 to 5:1.